Friday, October 10, 2014

A New Method for the Analysis of ppb Levels of Mercury in Air and Water



Accepted for presentation at Pittcon 2015
March 8-12, 2015
New Orleans, LA
Abstract Number: 1100 - 6
Session 1100 - Environmental - Portable Instrumentation
Day and Time: 0 2015 10:25 AM
Room 256


Authors: Jack Driscoll and Jennifer Maclachlan, PID Analyzers, LLC
Methodology:Other, gold film/photoionization
Application:Environmental
Primary Focus:Application
Title:A New Method for the Analysis of ppb Levels of Mercury in Air and Water
Keywords:
Air
Elemental Analysis
Environmental Analysis
Water
Nonspecific methods such as UV absorbance or fluorescence have been successfully used for the analysis of ppb concentrations of mercury in air and water. The unique amalgamation of mercury with gold and silver makes this possible. .Air samples are collected and only the mercury is reacted with the gold surface. Any impurities are purged through, then the amalgam is heated to desorb the mercury which is measured by the detector. 
We have used a very sensitive but nonspecific photoionization detector (PID) with a 10.6 eV lamp to measure mercury that has an ionization potential of 10.43 eV. The chemistry of the gold/mercury amalgam makes this method specific for mercury. The Permissible Exposure Limit (PEL) for Hg is 0.05 mg/m3 (0.408 ppm). Mercury permeation tubes were used to generate levels from 0.02 to 1 ppm. Preliminary data indicates a detection limit of > 10 ppb of Hg for the gold film photoionization detector (GFPID) analysis.
Water samples are analyzed using hydride generation with sodium borahydride to reduce the inorganic salts to elemental mercury that is efficiently detected by the PID. The EPA MCL for mercury in drinking water is 2 ppb. The  detection limit for Hg in water by hydride generation GFPID was 0.2 ppb.




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